Conventionally, in assembly of an electronic device, components such as a circuit board is fixed to a casing, using a cylindrical post attached to an inner bottom surface of the casing, for example, by crimping. A female screw is formed on an inner circumferential surface of the cylindrical post. A component having a screw hole formed therein is placed on the cylindrical post and they are screwed together so that the component is fixed to the casing via the post. However, since the post which is a part different to the casing is used, there is a possibility that the number of components and the cost are increased disadvantageously.
In contrast, for example, Patent Literature 1 discloses a configuration in which a circuit board is fixed without a post. Specifically, in Patent Literature 1, it is described that an attachment portion of a printed circuit board is formed by cutting and raising a part of a sheet metal frame and bending it. By attaching the circuit board directly to the sheet metal frame, it is possible to establish the grounding of the circuit board. Although a hole in the sheet metal frame formed by the cutting and raising can be an inlet through which foreign substances intrude from the outside, the hole is configured to be closed by a cover member.